Whether they're red, yellow or white, onions are versatile vegetables that can be used in a variety of different and delicious ways. Unfortunately, the way you cook them can't help you resolve onion indigestion. This issue primarily occurs because of the fermentable carbohydrate content in onions.
Onion Nutrition Facts
About 87 percent of onions produced in America are yellow onions, which are the most versatile type of onion. These onions can range from 4.5 inches to less than 1 inch in diameter. Yellow onions are often mild to moderate in flavor, but certain varieties are distinctly sweet.
The USDA states that 100 grams (3.5 ounces) of yellow onions typically has 132 calories, and 10.8 grams of fat — most of which come from healthy unsaturated fats like omega-3 and omega-6 fatty acids. Yellow onions also contain 1 gram of protein and 7.9 grams of carbohydrates. Out of these carbohydrates, 1.7 grams come from fiber.
Yellow onions primarily have vitamin B6 (12 percent of the daily value) and vitamin K (18 percent of the daily value). These onions have a variety of other essential vitamins and minerals, but most of those are only present in small amounts of between 1 and 4 percent of the daily value (DV).
Keep in mind that not all yellow onions have the same nutritional value. For example, the same amount (100 grams) of sweet yellow onions has 32 calories, 0.1 grams of fat, 0.8 grams of protein and 7.6 grams of carbohydrates. There are 0.9 grams of fiber within these carbohydrates.
Sweet yellow onions have no vitamin K or omega fatty acids, but do contain:
- 8 percent of the DV for vitamin B6
- 6 percent of the DV for vitamin B9 (folic acid)
- 5 percent of the DV for vitamin C
- 6 percent of the DV for copper
Onion Intolerance and Allergic Reactions
Typically, allergies produce a standard set of symptoms. According to the Mayo Clinic, allergies tend to cause issues like:
- Tingling and itching throughout the body, including in the mouth
- Hives, rashes and eczema
- Swelling of the lips, face, tongue and throat
- Trouble breathing and asthma-like symptoms, including wheezing
- Abdominal pain, diarrhea, nausea and vomiting
In some cases, allergies can be so severe that they close the airways and cause sudden drops in blood pressure. This is a sign of anaphylactic shock, which requires urgent medical care.
According to a November 2014 study in the Recent Patents on Inflammation and Allergy Drug Discovery Journal, onion allergies don't always produce the same symptoms compared to regular allergies. Instead, an onion allergy may result in health issues like dermatitis, asthma, and gum, eye and nose diseases.
Onions can also cause pollen-food allergy symptoms when ingested, because they have similar proteins to mugwort pollen. Essentially, this means that if you are allergic to mugwort pollen, you may react to onions, garlic and a variety of other fruits, vegetables and spices.
If you're experiencing onion indigestion, it's likely that you have a type of onion sensitivity. Such onion sensitivity often causes gastrointestinal symptoms like indigestion and can be from either or both immune responses or intolerance.
Depending on the severity of your symptoms, you may need to eliminate onions from your diet entirely. However, if your onion sensitivity is mild, you may simply need to find out the maximum amount you can consume before experiencing gastrointestinal side effects.
Onion Indigestion and Fermentable Carbohydrates
Most onions are primarily carbohydrates and contain minimal amounts of other macronutrients. Large amounts of these carbohydrates are fermentable short-chain carbohydrates, which are known as FODMAPs (or fermentable oligosaccharides, disaccharides, monosaccharides and polyols). According to an article published in 2016 in the journal Clinical and Experimental Gastroenterology, onions are particularly rich in the first type of FODMAP: oligosaccharides.
Many people can eat fermentable short-chain carbohydrates without experiencing any issues. However, not everyone can digest FODMAP-rich foods. People with chronic gastrointestinal problems like irritable bowel syndrome and people with malabsorption disorders are particularly sensitive to FODMAP-rich foods.
This is partly because FODMAP-rich foods aren't easily absorbed by the small intestine. They are then fermented as they pass through the gastrointestinal tract. This fermentation process can result in a variety of gastrointestinal problems. Gut issues like indigestion, bloating, gas, cramping and stomach pain are all common side effects.
If you regularly experience onion indigestion, it's very likely it's due to FODMAPs. Unfortunately, if you have onion intolerance of this type, it's likely that you're reacting to many foods — not just onions. The Journal of Clinical and Experimental Gastroenterology study says that a wide variety of plant-based products, including garlic, artichokes, leeks, beetroot, watermelon, peaches and most dried fruit contain oligosaccharides too.
Onions and Gastroesophageal Reflux Disease
According to a September 2017 study in the World Journal of Gastroenterology, onions are well-known for causing epigastric burning and heartburn. Their consumption often causes intestinal smooth-muscle dysfunction, which is another cause of indigestion.
Similarly, onions cause dysfunctions of the lower esophageal sphincter, like gastroesophageal reflux disease (GERD). According to Harvard Health Publishing, 19 million Americans have this condition.
If you have GERD, issues with your lower esophageal sphincter's functionality can cause stomach acid and digestive juices to enter your esophagus and irritate it. Stomach acid can even rise up the esophagus into your mouth. This can cause a range of other problems, including food regurgitation, laryngitis, dental erosions, coughing fits and asthma.
Although there are a variety of medications that can treat GERD, people with this condition will often be asked to make lifestyle changes too. These changes include drinking less alcohol, losing weight, not smoking and avoiding trigger foods, like onions, garlic and citrus fruits.
While it may be unpleasant to remove onions from your diet entirely, GERD can be serious if left untreated. This condition can result in esophagitis, the inflammation of the esophagus. Certain people with particularly severe esophagitis are even at an increased risk for esophageal cancer.
- Harvard Health Publishing: "GERD: Heartburn and More"
- World Journal of Gastroenterology: "Behavioral Gastroenterology: An Emerging System and New Frontier of Action"
- Clinical and Experimental Gastroenterology: "Efficacy of the Low Fodmap Diet for Treating Irritable Bowel Syndrome: The Evidence to Date"
- Journal for Nurse Practitioners: "Addressing the Role of Food in Irritable Bowel Syndrome Symptom Management"
- Nutrition Guide for Physicians and Related Healthcare Professionals: "Food Allergy and Intolerance: Diagnosis and Nutritional Management"
- Recent Patents on Inflammation & Allergy Drug Discovery: "Unusual Food Allergy: Alioidea Allergic Reactions Overview"
- Mayo Clinic: "Food Allergy"
- MyFoodData: "Nutrition Comparison of Sweet Onions and Yellow Onions"
- National Onion Association: "Seasons, Colors, Flavors, & Sizes of Onion"